Victim row refreshes for memories in electronic devices

Abstract

An electronic device includes a memory having a plurality of memory rows and a memory refresh functional block that performs a victim row refresh operation. For the victim row refresh operation, the memory refresh functional block selects one or more victim memory rows that may be victims of data corruption caused by repeated memory accesses in a specified group of memory rows near each of the one or more victim memory rows. The memory refresh functional block then individually refreshes each of the one or more victim memory rows.

What is claimed is: 
     
       1. An electronic device, comprising:
 a memory that includes a plurality of memory rows; and 
 a memory refresh functional block configured to perform a victim row refresh operation that includes:
 selecting one or more victim memory rows based on a summation of access counts for a specified group of two or more memory rows near each of the one or more victim memory rows exceeding a group access threshold; and 
 individually refreshing each of the one or more victim memory rows. 
 
 
     
     
       2. The electronic device of  claim 1 , wherein, when selecting the one or more victim memory rows, the memory refresh functional block is configured to:
 find, using a memory access count record, one or more candidate memory rows that are adjacent to one or more repeatedly accessed memory rows; and 
 select each of the one or more candidate memory rows as a victim memory row when the summation of access counts from the memory access count record for the specified group of two or more memory rows near that candidate memory row exceeds the group access threshold. 
 
     
     
       3. The electronic device of  claim 2 , wherein, when finding the one or more candidate memory rows, the memory refresh functional block is configured to:
 identify, using the memory access count record, one or more repeatedly accessed memory rows for which a respective access count exceeds an access threshold; and 
 select, as each of the one or more candidate memory rows, a memory row that is adjacent to a respective one of the repeatedly accessed memory rows. 
 
     
     
       4. The electronic device of  claim 3 , wherein the memory refresh functional block is configured to:
 sort access counts from the memory access count record into a sorted order from highest to lowest access counts; and 
 use the access counts in the sorted order for identifying the one or more repeatedly accessed memory rows. 
 
     
     
       5. The electronic device of  claim 4 , wherein the memory refresh functional block is configured to:
 find a highest access count from among access counts in the memory access count record; and 
 use only the highest access count for identifying a repeatedly accessed memory row. 
 
     
     
       6. The electronic device of  claim 4 , wherein the memory refresh functional block is configured to:
 halt the victim row refresh operation without selecting any victim memory rows and/or refreshing any victim memory rows when:
 no memory rows are identified for which the respective access count exceeds the row access threshold; or 
 none of the summations of access counts exceeds the group access threshold. 
 
 
     
     
       7. The electronic device of  claim 3 , wherein the memory refresh functional block is configured to:
 update respective access counts associated with memory rows in the memory access count record based on memory accesses performed in those memory rows. 
 
     
     
       8. The electronic device of  claim 1 , wherein the one or more victim memory rows may be victims of data corruption caused by repeated memory accesses in the specified group of two or more memory rows near each of the one or more victim memory rows. 
     
     
       9. The electronic device of  claim 1 , wherein, when individually refreshing each of the one or more victim memory rows, the memory refresh functional block is configured to:
 cause data stored in memory elements in each of the one or more victim memory rows to be recharged or restored so that existing data stored in each of the one or more victim memory rows is retained in the memory elements. 
 
     
     
       10. The electronic device of  claim 1 , wherein the memory refresh functional block is configured to commence a respective victim row refresh operation at each of two or more different times. 
     
     
       11. A memory refresh functional block configured to perform a victim row refresh operation, the victim row refresh operation comprising:
 selecting one or more victim memory rows based on a summation of access counts for a specified group of two or more memory rows near each of the one or more victim memory rows exceeding a group access threshold; and 
 individually refreshing each of the one or more victim memory rows. 
 
     
     
       12. The memory refresh functional block of  claim 11 , wherein the memory refresh functional block is configured to, when selecting the one or more victim memory rows:
 find, using a memory access count record, one or more candidate memory rows that are adjacent to one or more repeatedly accessed memory rows; and 
 select each of the one or more candidate memory rows as a victim memory row when the summation of access counts from the memory access count record for the specified group of two or more memory rows near that candidate memory row exceeds the group access threshold. 
 
     
     
       13. The memory refresh functional block of  claim 12 , wherein the memory refresh functional block is configured to, when finding the one or more candidate memory rows:
 identify, using the memory access count record, one or more repeatedly accessed memory rows for which a respective access count exceeds an access threshold; and 
 select, as each of the one or more candidate memory rows, a memory row that is adjacent to a respective one of the repeatedly accessed memory rows. 
 
     
     
       14. The memory refresh functional block of  claim 13 , wherein the memory refresh functional block is configured to:
 sort access counts from the memory access count record into a sorted order from highest to lowest access counts; and 
 use the access counts in the sorted order for identifying the one or more repeatedly accessed memory rows. 
 
     
     
       15. The memory refresh functional block of  claim 14 , wherein the memory refresh functional block is configured to:
 find a highest access count from among access counts in the memory access count record; and 
 use only the highest access count for identifying a repeatedly accessed memory row. 
 
     
     
       16. The memory refresh functional block of  claim 14 , wherein the memory refresh functional block is configured to:
 halt the victim row refresh operation without selecting any victim memory rows and/or refreshing any victim memory rows when:
 no memory rows are identified for which the respective access count exceeds the row access threshold; or 
 none of the summations of access counts exceeds the group access threshold. 
 
 
     
     
       17. The memory refresh functional block of  claim 13 , wherein the memory refresh functional block is configured to:
 update respective access counts associated with memory rows in the memory access count record based on memory accesses performed in those memory rows. 
 
     
     
       18. The memory refresh functional block of  claim 11 , wherein the one or more victim memory rows may be victims of data corruption caused by repeated memory accesses in the specified group of two or more memory rows near each of the one or more victim memory rows. 
     
     
       19. The memory refresh functional block of  claim 11 , wherein, when individually refreshing each of the one or more victim memory rows, the memory refresh functional block is configured to:
 cause data stored in memory elements in each of the one or more victim memory rows to be recharged or restored so that existing data stored in each of the one or more victim memory rows is retained in the memory elements. 
 
     
     
       20. The memory refresh functional block of  claim 11 , wherein the memory refresh functional block is configured to commence a respective victim row refresh operation at each of two or more different times. 
     
     
       21. A method for performing victim row refresh operation in an electronic device that includes a memory with a plurality of memory rows, the method comprising:
 selecting one or more victim memory rows based on a summation of access counts for a specified group of two or more memory rows near each of the one or more victim memory rows exceeding a group access threshold; and 
 individually refreshing each of the one or more victim memory rows.